By Thomas FerraroWASHINGTON (Reuters) - Top aides to President Barack Obama on Sunday urged Democratic and Republican lawmakers to set aside political differences and give anticipated final approval this week to a massive economic stimulus package."If there was ever a moment to transcend politics, this is that moment," Larry Summers, head of the White House National Economic Council, told "Fox News Sunday."Yet, with the world watching to see how the new president and Congress respond to the worst U.S. recession in 70 years, more political fireworks were certain at the U.S. Capitol.Squabbling will resume on Monday when the Democratic-led Senate, with the help of just a few Republicans, votes to end debate on an $827 billion rescue package and clear the way for passage of the measure on Tuesday.Negotiators will then seek to resolve differences between the Senate bill and an $819 billion version of the measure earlier passed by the House of Representatives without any Republican support."Negotiations will be difficult, but fun to watch," a Republican aide said, citing battles on the size and scope of a final package of tax relief and new spending.Senator Charles Schumer of New York, a member of the Democratic leadership, told CNN's "State of the Union" that the House, Senate and the White House "all agree there has to be some give and take."Obama has demanded that a final bill be on his desk by next Monday to sign into law.The political drama is being played out as the Democratic and Republican parties are at odds ideologically, with both claiming popular support.Republicans stand accused of having driven the country into an economic mess under President George W. Bush, and of pushing a tax-cut agenda that failed to revive the economy and instead helped create a record federal deficit.Foes accuse Obama's Democrats of seizing on the economic crisis to pump cash into their pet projects and "big government" social agenda under the guise of creating jobs.The White House itself has been vague about what it wants other than a plan with enough support by Democrats and Republicans to win passage and create jobs.Appearing on CBS's "Face the Nation," Christina Romer, another top Obama fiscal adviser, said, "If we can get this (rescue) package through, we can turn it (the economy) around and be back on the road to growth."FAILURE WILL BE "CATASTROPHIC"Warning that failure is not an option, Romer said if the package falls apart, "I think it would be -- the word the president used was catastrophic."Seeking to keep Congress focused on the package, the Obama administration on Sunday put off Treasury Secretary Timothy Geithner's announcement of a keenly awaited and separate bank rescue plan that had been expected to be made on Monday."We need to get the stimulus package through and we do know that any package to get the economy healthy is going to be more effective if we get the banks healthy, because we have got to get them lending again," Romer said.Summers, appearing on ABC's "This Week," added, "There's a desire to keep the focus right now on the economic recovery program, which is so very, very important."Democrats seem to have the votes needed to prevail on the economic stimulus package, the centerpiece of Obama's plan to revive the U.S. economy.Yet Republicans ripped into Obama, charging he has fallen short of his campaign vow to work with them and promote a new spirit of cooperation in Washington."This agreement is not bipartisan," scoffed Republican Senator John McCain, who lost the 2008 White House race to Obama.Appearing on CBS's "Face the Nation," McCain argued that the package is twice as much as is needed. He also noted just three Republicans in the 100-member Senate back it.McCain said he believed the rescue package "may help a bit," but will also saddle future generations with increased federal debt.Senate Budget Committee Chairman Kent Conrad, a North Dakota Democrat, appearing on the same show, accused many Republicans of playing politics."I think most of them have made a political calculation that it's better to be in opposition. And you can see that on a political basis because, look, this economy is in desperately serious shape," Conrad said.Republican Senator John Ensign said he expected the Senate bill to pass. But Ensign said he and other Republicans want time to go through the compromise package that was reached on late Friday and put into written legislation late on Saturday."This is almost a trillion dollars. You don't get do-overs with a trillion dollars," Ensign told NBC's "Meet the Press."(Additional reporting by Mark Felsenthal and Nancy Waitz; Editing by David Wiessler)